package Sy;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public class Sy2 {
 public static List<Student> filterAgeThan20(List<Student> list) {
 // 找出年龄大于20的学生;
 List<Student> newList = new ArrayList<>();
 for (Student s : list) {
 if (s.age > 20) {
 newList.add(s);
 }
 }
 return newList;
 }

 public static List<Student> filterAgeThan20_1(List<Student> list) {
 // 找出年龄大于20的学生;
 return list.stream().filter(s -> s.age > 20).collect(Collectors.toList());
 }

 public static List<Student> filterMajorIsComputer(List<Student> list) {
 // 找出专业是计科的学生;
 return list;
 }

 public static List<String> mapName(List<Student> list) {
 // 获取所有学生的姓名
 return new ArrayList<>();
 }

 public static Map<String, List<Student>> groupByMajor(List<Student> list) {
 // 按专业分组
 return new HashMap<>();
 }

 public static Map<Integer, List<Student>> groupByAge(List<Student> list) {
 // 按年龄分组
 return new HashMap<>();
 }
}